Charge Processing Fee to Certain Levels

my_pmpro_fee-to-certain-levels.php

<?php
/**
 * If user checkouts in certain levels, add a processing fee.
 * 
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_add_account_creation_fee( $checkout_level ) {
	if ( ! function_exists( 'pmpro_getMembershipLevelsForUser' ) ) {
		return $checkout_level;
	}
	
	// Skip users with no existing level, i.e., new users.
	$maybe_level = pmpro_getMembershipLevelsForUser();
	if ( ! $maybe_level ) {
		return $checkout_level;
	}
	
	if ( 3 == $checkout_level->id || 12 == $checkout_level->id ) {
		$checkout_level->initial_payment += 2.50;
	}

	return $checkout_level;
}
add_filter( 'pmpro_checkout_level', 'my_pmpro_add_account_creation_fee' );